Classification of Stellar Spectra
Student Data Sheets
Names:
Part I Emission Spectra of Rarefied Gases
Color
Red
Blue
Green
Yellow
Violet
Orange
Wavelength, λ (Å) Energy, Eλ (J)
6800
4500
5200
5800
4000
6000
1.
What is the main difference in what you saw when observing a light source like a light bulb or
ceiling light compared to a discharge tube? Why the difference, if any?
2.
Which of the discharge tubes that you observed had the highest energy photons? Lowest energy?
3.
Why does the neon gas glow red when you look at it without the spectrometer? Why does the
mercury lamp look blue without the spectrometer?
4.
Observe the spectrum of a fluorescent ceiling lamp again. Comparing your measurements to the
earlier measurements you made with the discharge tubes, can you identify the gas inside the
fluorescent tube? Give reasons to support your conclusion.
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Classification of Stellar Spectra
Student Data Sheets
Names:
ELEMENT
Emission line 1: Wavelength =
Emission line 2: Wavelength =
Emission line 3: Wavelength =
Observed Energy =
Observed Energy =
Observed Energy =
Calculated Energy =
Calculated Energy =
Calculated Energy =
Observed Energy =
Observed Energy =
Observed Energy =
Calculated Energy =
Calculated Energy =
Calculated Energy =
Observed Energy =
Observed Energy =
Observed Energy =
Calculated Energy =
Calculated Energy =
Calculated Energy =
Observed Energy =
Observed Energy =
Observed Energy =
Calculated Energy =
Calculated Energy =
Calculated Energy =
ELEMENT
Emission line 1: Wavelength =
Emission line 2: Wavelength =
Emission line 3: Wavelength =
ELEMENT
Emission line 1: Wavelength =
Emission line 2: Wavelength =
Emission line 3: Wavelength =
ELEMENT
Emission line 1: Wavelength =
Emission line 2: Wavelength =
Emission line 3: Wavelength =
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Classification of Stellar Spectra
Student Data Sheets
Names:
Part II Spectral Classification of Main-Sequence Stars
a. Choose any point on the continuum of HD 124320 and record its wavelength and intensity.
Wavelength _____________________ Intensity ____________________
b. Measure the wavelength and intensity of the deepest point of the deepest absorption line in the
spectrum of HD 124320.
Wavelength _____________________ Intensity ____________________
c. Question: If you were to look at this range of wavelengths with your eyes, what color would they
appear? ___________________________________________________
Spectral types in the atlas:
a. As you look through the stars in the Atlas, can you tell from the continuum which spectral type is
hottest? Identify the hottest spectral type? ________________________.
Explain your answer. (Remember that, on all these graphs, 3900 Å is at the left, and 4500 Å is at the
right).
b. At about what spectral type is the peak continuum intensity at 4200 Å ? (4200 Å is about the
middle along the x axis).
_______________________________________________
c. What would be the temperature of this star?
________________________________________________.
Your estimate of the spectral type of HD124320_________________.
Give reasons for your answer. ( For this example: The strength of lines at 4340.4 Å and 4104 Å are
almost exactly those of type A1 or A5, and the strength of the 3933 Å line lies somewhere between
them.).
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Classification of Stellar Spectra
Student Data Sheets
Names:
Data Table: Practice Spectral Classification
STAR
SP TYPE
REASONS
HD124320
A3
HI lines very strong, CaII line betw. A0 and A5
HD 37767
HD 35619
HD 23733
O1015
HD 24189
HD 107399
HD 240344
HD 17647
BD +63 137
HD 66171
HZ 948
HD 35215
Feige 40
Feige 41
HD 6111
HD 23863
HD 221741
HD 242936
HD 5351
SAO 81292
HD 27685
HD 21619
HD 23511
HD 158659
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Classification of Stellar Spectra
Student Data Sheets
Names:
Part III Taking Spectra Using A Simulated Telescope And Digital Spectrometer
Coordinates of Observed Star
Right Ascension:
_________________________
Declination:
_________________________
Apparent Magnitude:
_________________________
File name for first star spectrum:__________________________.
Star 2:
Coordinates:
Right Ascension
__________________
Declination
__________________
Spectrum stored in file named
______________________.
Spectral Type of Two Unknown Stars
Star #
Object Name
Spectral Type
Reasons
1
2
Star
Spectral Type
Absolute
Magnitude, M
Apparent
Magnitude, m
Distance in
parsecs
Question: Are the stars in the above table members of the Milky Way Galaxy of which our Sun is a
part? (The Diameter of the Milky Way is about 30, 000 parsecs)_______________.
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